CHAP. XXII.] 
MOLLUSCA. 
511 
Family 16.— HALIOTID^. (6 Genera, 106 Species), 
Distribution. — The Ear-shells are most abundant in the 
Indian and Pacific Oceans ; some are found on the east coasts 
of the Atlantic, but there are .very few in the West Indies. 
Ianthina (10 sp.) consists of floating oceanic snails found in the 
warm parts of the Atlantic. Three other genera are fossil, and 
there are near 600 fossil species of this family ranging from the 
Lower Silurian to the Pliocene formations. 
Family 17. — FISSUKELLIDZE. (5 Genera, 200 Species). ' 
Distribution; — All seas. Puncturella (6 sp.) is confined to 
Northern and Antarctic seas; Rimula to the Philippines ; and 
Parmophorus (15 sp.) from the Cape of Good Hope to the 
Philippines and New Zealand. There are about 80 fossil 
species, ranging from the Carboniferous formation to the 
deposits of the Glacial epoch. 
Family 18.— CALYPTE^EID^E. (4 Genera, 125 Species). 
Distribution. — The Calptrseidm, or Bonnet-limpets, are 
found on the coasts of all seas from Norway to Chili and 
Australia ; but are most abundant within the Tropics. The 
genera are all widely scattered. There are 75 fossil species, 
ranging from the Devonian to recent formations. 
Family 19. — PATELLIDZE. (4 Genera, 254 Species). 
Distribution. — The Patellidas, or Limpets, are universally 
distributed, and are as abundant in the temperate as in 
tropical seas. There are about 100 fossil species, ranging from 
the Silurian to the Tertiary formations. 
